WITHIN-SLOPE VARIABILITY OF GROUND HEAT FLUX, SUBARCTIC YUKON

Abstract

This study examined local variability of heat flux within a north-facing hillslope in Wolf Creek basin, Yukon, during the thawed season of 1997. Ground heat flux was calculated by: (1) assessing vertical conduction and convection inputs (Q_Gv) using near-surface temperature gradients and rainfall and (2) combining the sensible heat from ground temperature change with the latent heat associated with melting ground ice (Q_Gs). Seasonally, the coefficient of variation (cv) of Q_Gv was 20%, with most of the variation accounted for by changes in wetness and soil properties. Vertical convection of heat by infiltrating rainfall accounted for less than 3% of Q_Gv. Measurements of Q_Gs, which incorporate lateral heat transfer associated with groundwater flow, has a cv of 40%. Footslope sites do not have permafrost because of downslope advection of heat from groundwater and Q_Gs was 2 to 3 times greater than upslope permafrost sites. Q_Gv and Q_Gs were similar at the upslope locations, however, the active layer depth varies depending on the ice content of the frozen soil. [Key words: ground heat flux, permafrost, subarctic, energy balance.]